Algae control in ponds

The key to successful algae control in ponds is to understand how algae work. Algae needs water, light, carbon dioxide, oxygen and nutrients to survive. Water and carbon dioxide is typically available in ample amounts in a pond, and an alga produces more oxygen than it consumes since oxygen is a bi-product of photosynthesis. The limiting factors are therefore normally light and nutrients. Light can be restricted in various ways, but it is often fairly difficult unless you wish to move your entire garden pond to a more shadowy part of your garden or arrange some type of sun protection for the pond. In this article we will therefore focus on nutrients and their role for algae control in ponds.

When it comes to nutrients, most types of algae need carbon, nitrogen and phosphorus. There is normally plenty of carbon and nitrogen available for algae in ponds, but phosphorus can be hard to find and the amount of phosphorus in a pond is therefore often a key factor when it comes to determining how much algae the pond can support. Restricting the amounts of phosphorus that enters the water can therefore be used for algae control in ponds.

This list includes a few suggestions on how to control algae growth in ponds by limiting the amounts of available nutrients. You don’t have to do them all; in many cases significant improvements can be seen in gardens where only a handful of the suggestions have been put into action. Sit down and try to assess which methods that would suit your particular garden pond or large pond best.

Algae in pond

Avoid using phosphorous-rich fertilizers around the pond. Rainwater can easily transport fertilizers to the pond during heavy rains.

Build a protective earth embankment or similar around your pool to prevent rainwater streams from reaching the pond. If you find the embankment ugly, you can always plant it with beautiful flowers and turn it into a stylish flower bed.

Create a buffer strip around the pond by planting shrubs or high grasses.

Dig diversion trenches to redirect run-off.

Fill the pond with live plants. Live plants and algae will compete for the same nutrients and there will therefore be less available nutrients for the algae in a pond with lush aquatic plant growth.

If this is not enough, you can try combating the algae by filling with pond with animals that likes to eat algae. There are for instance a lot of suitable pond fishes that loves to feast on algae, and invertebrates such as snails can also be used for algae control in ponds. It is important to first identify the problematic algae, because different algae eaters have different preferences. It is also important to pick an algae eater that will thrive in your particular pond, i.e. an algae eater that appreciates the water temperature, pH-value etcetera in your pond.